Bob Easton

Archive for November, 2009

Scarf or Scarph – The joining of two timbers by beveling the edges so the same thickness is maintained throughout the length of the joint.

All of the plywood has been reduced to strips and chunks of sizes appropriate for fabricating the various parts.

Using 8 foot long lumber to make a 13 foot long boat needs some method of lengthening lumber. Scarphing is the answer. It has been a while since I beveled lumber for scarph joints, so I did a trial run with a few small plywood offcuts. The recommended bevel ratio is 8:1. For the 6mm (1/4 inch) plywood this works out to 1 and 1/2 inch of length. So, I stacked 4 boards with 1 and 1/2 inch offsets and used a few brads to immobilize them. (Hey you guys with the maple / mahogany / purpleheart bench tops that look like boardroom furniture, see why a lumberyard bench is really versatile? Neither my bench nor I cry when I drive nails into it.)

By using 4 boards, the correct planing angle is automatic. The stepped stack sets the right angle and one has to work hard to make it wrong. I started with a block plane, but quickly switched to the jack plane. The jack’s longer nose makes the work more accurate. Extra sharpness is really helpful for this work. Planing at an angle is also helpful. The multiple grain directions of the ply layers are handled much easier with an angled approach. Keep going until there’s a smooth ramp. The plies themselves act as indicators of even planing. They get all wavy when the work is uneven. Keen observers will see some tear out on the fine edge. That’s not a problem, as we’ll see during glue up.

The test of a good job comes from joining the bevels and seeing if the plies of both pieces line up well. Here we see a couple of pieces dry fitted. Looking great. So, let’s move on and plane all the pieces needing scarphing. The bottom is 6mm (1/4 inch) and needs one scarph. There are four 4mm (5/32 inch) hull planks needing scarphs. There are five in all.

Preparing all the bevels wasn’t much work. Actually, it was a lot less work than getting to a similar point with the previous boat where I invested a lot of time in resawing the lumber.

Next comes “glue up.” This is the time when woodworkers usually feel the pressure of glue that’s starting to cure faster than they can get parts aligned. I still have some West System epoxy left from the previous build and am using their slow version. Still, pot life is rather short, and it is good to get all parts stacked up in the right sequence for use, and to have all auxiliary stuff (plastic sheets, clamps, cauls, etc.) close at hand. Rehersal sometimes helps. Yep, I rehearsed this one since I intended to do all joints in one sesson.

I used two batches of epoxy. The first was the standard mix. I brushed this onto all faying surfaces but did not join them. This was to feed those hungry surfaces, essentially priming them so they wouldn’t dry out without providing adhesion. The second batch included enough wood flour to thicken the epoxy to the consistency of mustard. This makes a robust mixture that won’t easily run out of the joint while it cures. It also helps fill in at the very fine edge where there is some tear out. I applied this liberally to one surface for each join and then joined pieces together. A plastic trash bag protects the bench from having planks glued to it. Two hull planks, side by side, made the first pair of joins. Add another trash bag. Do the next two planks side by side. Add another trash bag and do the join for the wide bottom board. Lastly add another trash bag, stack a caul on top and apply some clamp pressure. Epoxy doesn’t need a lot of clamping pressure. Doing so squeezes too much out an leaves a weak joint.

The little bit of glue left after these joins was just enough to glue up two pairs of “hanging knee” parts. We’ll see pictures of them later.

So now, we sit back and watch glue cure … every bit as exciting as watching paint dry.

In which I talk about starting a new boat, and cutting plywood without beer.

Following the successful build and launch of “Eva Won,” I’m now getting started on “Eva Too.” This one is another decked canoe. It will be 13 feet long and built mostly of marine grade plywood using the “stitch and glue” technique. The design is the Mill Creek 13 from Chesapeake Light Craft. This will be Eva’s boat, and she really liked the Mill Creek’s stability rating, its good looks, and its stability rating, and most of all its stability rating.

CLC sells complete kits with all the parts completely cut out, but we’re not the “paint by numbers” type. I’ll be building from their plans but doing all the component prep and construction work myself. The plans consist of six sheets and a hefty spiral bound instruction book. Everything looks straightforward and there are literally hundreds of Mill Creek 13s already built. So, I’m confident this will be a good build. Just saying that insures we’ll probably hear stories along the way.

Stitch and glue boats are built from marine grade plywood. The boat building folks up in Maine advise that anything labeled “marine” means only that it costs three times more than normal. This plywood meets that description. Yet, there really is more to it. There is a fairly rigorous standard which requires knot free face veneers, absolutely no core voids, minimal ply thicknesses and counts, waterproof glues (duh), and other size tolerances.

My plywood is Bruynzeel Occume which uses gaboon as the face veneer. While not a true mahogany, gaboon has a similar appearance, is cheaper, and is far more plentiful than mahogany. M. L. Condon in White Plains NY is the lumber yard I frequent. I’ve seen people complain that Condon’s prices are high, and they are. However, once one factors in transportation the price differences disappear. Buying from a distant supplier entails transportation charges of $150-200, and I can drive to White Plains for less than $15. Add to that the ability to walk the yard and hand pick material and Condon works out very well. While I was handing sheets down from an upper level bin to a yard worker below, I mentioned that the top sheet in that stack was a “bit ratty.” It had some edge damage that extended 4-5 inches into the sheet. He said, “Hey. I’d like to get that sheet out of here, how about I knock of $14?” Being familiar with the cut plans, I knew I could work around that damage and gladly accepted a 20% savings. This meager pile of lumber is almost all I’ll need. It is three sheets of 4mm plywood, one sheet of 6mm plywood, and an ash 1 by 6 of which I’ll use a pittance (discounted for that knot). Another stick of spruce or fir from “the Borg” will provide internal framing.

It’s been a very long time since I cut plywood, and the memory makes only part of the experience appealing. Decades ago, I had no saw benches, a couple of sheets of plywood to cut, a circular saw … and a six pack of something cheaper than Budwiser. So, I spread out those six cans strategically, balanced precariously over the wobbly arrangement and went at it with the noisy spinning thing. I survived with all fingers, but resolved, while drinking my bench, to avoid cutting plywood as much as possible. No problem today, no need for a beer can bench. By some unforeseen and unplanned stroke of genius I built both my workbench and the previous boat’s strongback to within 1/4 inch of the same height. They now become two very sturdy sawbenches, upon which a monkey on all fours can use a simple handsaw to make easy work of breaking down the plywood.

We’ve had a comfortable Fall this year. The woolly worms are woollier. Deer fur is darker this year than in others. The Old Farmer’s Almanac predicts a colder winter for the Northeast, and Al Gore is too busy PhotoShopping hurricanes to notice. Starting a project that uses lots of epoxy in an unheated workshop nearly guarantees immediate and precipitous temperature decline. We’ll see…

We live within a hundred yards of a woodlands, a large state park. My better half and I went hiking there a couple of days ago. On the way back home, I spotted a small log hiding under a guard rail along the roadside. A maintenance crew goes along the park roads every fall trimming limbs and trees that might fall upon the roadway during ice storms. They usually saw logs into firewood length and leave them to be picked up by whoever wants them. Someone missed this little log of black locust. I could see a couple of mallets inside that log, so I picked it up and carried it home (which worked off at least a Snickers bar).

I wanted to reduce this log a bit to help it dry without splitting too much. I would really like to rive the wood rather than cut it, but there are not yet any tools for green woodworking in my shop. My solution was to use a coarse setting of my #40 scrub plane to make flats on either side of the log. Then, a few passes through the band saw reduced it to pieces I think will be useful for mallet heads and handles. Those are set aside to dry for awhile.

I’m not certain on the design yet. Maybe a sawed head, maybe a turned head. Of course, for the turned head I don’t have a lathe that’s large enough. I’ve been wanting to build one of “St. Roy’s” spring pole lathes. To be continued…

A scraggly old broken spring hook (tool “G” at this link), with the broken off end roughly resharpened to a point, served as a scratching tool for many years. Now, with the ability to neatly grind metal, and a little scrap of oak, it takes new form, a finished scratch awl. There’s really not much to it. I turned the handle in a small model making lathe. The awl itself is that old tool reground and polished. 3M microabrasive film is fantastic for polishing. The ferrule was donated by a self-sacrificing Pentel mechanical pencil. Finish is several coats of danish oil.

Yes, it is small. It fits the palm easily. As shown in this picture, I was using it to prick through a paper pattern to prepare for cutting a boat part.

Someday… Someday, I’m going to need a router plane. Router planes are used to clear the waste from a dado groove. I really don’t need the plane today, but have some projects in mind for the future that will need dado joints.

I based this plane (also called an “old woman’s tooth”) on an example made by Derek Cohen. A bit of 5/4 ash left over from the Fiddlehead boat was the starting point. Shaping was much as Derek described; drill a few holes, cut the outline with the shopmade turning saw, refine with rasps. Now that I can shape metal, the tooth / blade was shaped from a hex key. Hand cranking the grinder to shape the blade burned off a hand full of mini Tootsie Rolls. A screw insert and a thumb screw were the last of the parts. A couple of coats of boiled linseed oil, followed by a coat of danish oil finished the job.

Yes, it cuts as intended. This hex key yielded a 1/4 inch wide blade, which will be handy for the intended projects. The method used to set the depth of cut is to elevate the tool on a couple of old business cards and then drop the blade to the wood surface and tighten the thumb screw. Now, remove the cards and cut. Repeat til done. By the way, it is a real good thing to cut from the outsides of a groove toward the center. That avoids tearout at the edges.

For those who have no old business cards for depth setting, use two aces out of a deck of playing cards. Leave them in the shop, so the next time you have friends over for poker, you know where at least two of the aces are.

Old tool galoots gloat when they get a good tool at a very good price. Lesson of this one: Be patient. Wait for the good one.

My shop has been without a grinder, until very recently. The chisels have been sharpened enough to lose their original concave grind. It was time.

Did you know that you can set up a “Saved search” on eBay, and have it run once a day for months and months? That’s what I did when looking for a hand cranked grinder. eBay has plenty of these, and most are in pitiful shape. So, I waited and watched the daily search results, and waited and watched, and waited and watched.

A few weeks of daily searches yielded this “B&C Universal” grinder. It looked to be complete (most aren’y) and in decent shaped. It’s amazing how many grinders are missing their tool rests, and how many sellers don’t know to take pictures of that part of the grinder. Know what you are looking for because many of the sellers don’t know what they’re selling.

The sweetest part of this deal is that I ended up being the only one to bid and got it at the seller’s minimum bid, $9.99. It arrived a few days later and proved to be in very good shape. This grinder must have set idle on someone’s bench for decades. It shows virtually no wear. I know it sat idle from seeing an oil streak that ran down the side of the flange holding one side of the stone. A well used tool would have had that oil more evenly spread. There is some paint pitting, and there was some rust. The stone was like new, the edge still square, no chips no ruts, and it passed the ring test. The gears are angle (spiral?) cut, not straight, making for very smooth running.

Cleanup was easy. This is the first time I’ve used vinegar for rust removal, and was very pleased with how well it worked. Mineral spirits did the rest. I decided not to strip and repaint, but to put this tool immediately to use.

Now, can anyone tell me more about it? The metal dish used as a guide for sharpening knives and scissors had a decal saying “B&C Universal” and “No Skill Required.” On the side of the gear case is part of a logo. It is a diamond shape with a “B” fitted into the left point, and a “C” nested in between the “B” and the right point. Most of the word “Bridgeport” appears under the right side of the diamond. Yes, that probably suggests Bridgeport Connecticut. Bridgeport has long been famous for tool making. So, who in Bridgeport made “B&C” tools? Thanks for any information.

As always, click any picture to see a larger version.

Lastly, note a very interesting feature (see first picture). The grinder has a tool rest support arm that allows attaching the rest on either side of the wheel. The rest can be easily moved from one end to the other, making it the only ambidextrous grinder I saw during my time waiting for a good one.

How does it work? Very well. Better than I expected. Of course, getting used to cranking with one hand and tool holding with the other was a bit like learning to dance the Cha-Cha using only one leg. My chisels are sharp again, but you still don’t want to see me dance.